#include <stdio.h>
#include <string.h>

char *MyStrstr(char *s1,char *s2)
{
    for(int i = 0; s1[i] != '\0'; i++)
    {
        int flag = 0;
        for(int j = 0; s2[j] != '\0'; j++)
        {
            {
                if(s1[i+j] != s2[j])
                {
                    flag = 1;
                    break;
                }
            }       
        }
        if(flag == 0)
        {
            return (s1+i);
        }
    }
    return NULL;
}


int main()
{
    char *a = "hello";
    char *b = "0l";
    printf("%x %x\n",a,MyStrstr(a,b));
}